1. The Field of the Invention
The present invention relates to a tube coupling comprising a body having an open proximal end and a throughway to receive a tube, in use, the body having at least one lateral recess extending outwardly from an internal wall; an O-ring retained by the body distally of the or each recess and surrounding the throughway; a collet inserted into the proximal end of the body, the collet comprising a ring and at least one distally projecting collet leg, the or each collet leg being received in a respective lateral recess in the body and having a tooth facing the passageway, the body and leg being arranged such that proximal movement of the collet with respect to the body causes the or each finger to deflect inwardly. Such a coupling will subsequently be referred to as being “of the kind described”.
2. The Relevant Technology
A tube coupling of the kind described is well-known in the art. One example of such a coupling is illustrated in FIG. 1, which represents a product sold by John Guest as part of the “Underground” range.
As illustrated in FIG. 1, the body 1 is of tubular construction and has lateral recesses provided by four windows 2. An O-ring 3 is placed into the body 1 and rests in a recess (not shown) which is beyond the windows 2. An optional spacer washer 4 is fitted in the body 1 between the O-ring 3 and the windows 2 and a collet 5 is pushed into the tubular body 1 to complete the assembly. The collet comprises a collet ring 6 and four distally projecting collet legs 7, each of which locates within a respective window 2.
As is well-known in the art, a tube is pushed into the coupling from the collet end through the throughway to a position beyond the O-ring 3. The O-ring then seals against the outer face of the tube. Pulling on the tube in the proximal direction causes teeth 8 on the collet legs 7 to bite into the tube such that the collet 5 is drawn proximally together with the tube. Cam surfaces 9 on the collet legs 7 co-operate with the proximal edges of respective windows 2 in order to deflect collet legs 7 inwardly to produce a clamping force on the tube which increases with the pulling force on the tube to provide a secure coupling.
In order to release the tube from the coupling, the collet 5 is pushed distally and held in that position so that the teeth 8 are disengaged from the tube which can then be readily withdrawn.
As is apparent from FIG. 1, in order to assemble the coupling, the O-ring 3, spacer washer 4 and collet 5 are sequentially inserted into the housing 1. The collet 5 must be correctly aligned so that the collet legs 7 line up with their respective windows 2. If the collet 5 is not inserted correctly, the legs 7 can be damaged in use, or the collet 5 could fall out.
The present invention is directed to an improvement of a tube coupling of the kind described which is designed so that it is impossible to insert the collet in an incorrect alignment.